import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

public class ABADemo {
    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);
    static AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(100 ,1);

    public static void main(String[] args) {
        System.out.println("================以下是ABA问题的产生========================");

        new Thread(() -> {
            atomicReference.compareAndSet(100, 101);
            atomicReference.compareAndSet(101, 100);
        }, "t1").start();

        new Thread(() -> {
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println(atomicReference.compareAndSet(100, 2019) + "\t" +  atomicReference.get());
        }, "t2").start();

        System.out.println("================以下是ABA问题的解决========================");

        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName() + "\t第一次版本号：" + stamp);

            // 暂停1秒钟t3线程
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (Exception e) {
                e.printStackTrace();
            }

            atomicStampedReference.compareAndSet(100, 101, atomicStampedReference.getStamp(), atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName() + "\t第二次版本号：" + atomicStampedReference.getStamp());

            atomicStampedReference.compareAndSet(101, 101, atomicStampedReference.getStamp(), atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName() + "\t第三次版本号：" + atomicStampedReference.getStamp());
        }, "t3").start();

        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName() + "\t第一次版本号：" + stamp);

            // 暂停1秒钟t3线程
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (Exception e) {
                e.printStackTrace();
            }

            boolean result = atomicStampedReference.compareAndSet(100, 2019, stamp, stamp+1);
            System.out.println(Thread.currentThread().getName() + "\t修改成功否：" + result);
        }, "t4").start();


    }
}
